Diurnal variation in peak expiratory flow rate among workers exposed to toluene diisocyanate in the polyurethane foam manufacturing industry.

The diurnal variation in peak expiratory flow rate (PEFR) was studied in 26 mixers from eight factories making polyurethane foam, who were exposed to toluene diisocyanate (TDI), and 26 unexposed controls matched for age, race, and smoking. They were all men. The mean diurnal variation in PEFR of the mixers was 6.2%, which was significantly higher than the 4.3% for controls. Six mixers had a diurnal variation of greater than 15% on at least one day compared with none among the controls. There was, however, no overt cause of occupational asthma. All but one of the 24 environmental samples taken exceeded the short term exposure limit of 0.02 ppm for TDI. This accounted for the high prevalence (50%) of irritative symptoms such as cough and eye irritation. Forced expiratory volume in one second (FEV1) and FEV1/forced vital capacity (FVC) (%) was negatively correlated with duration of exposure to TDI. Foam workers may still have high exposure to TDI, high prevalence of irritative symptoms, increased diurnal variation in PEFR and evidence of chronic airway obstruction, particularly in those with greater than or equal to 10 years of exposure.     

Blood cholinesterase levels among agricultural workers in four Asian countries

In this study whole blood cholinesterase activities were determined (tintometric method) of agricultural pesticide users exposed to organophosphorus compounds in Indonesia, Malaysia, Sri Lanka and Thailand. Analysis of the data demonstrated a universal relationship between cholinesterase levels and the time between the last exposure to organophosphorus compounds and the day of blood collection for cholinesterase determination. It is suggested that it takes approximately 5 days before whole blood cholinesterase levels revert to their normal values. No relationship between whole blood cholinesterase levels and the sex of pesticide users was demonstrated except in Sri Lanka where female sprayers had lower values. It is suggested that these lower values are associated with the anaemic status of female agricultural workers. No relationship between whole blood cholinesterase level and age was demonstrated. The measurement of pre-exposure cholinesterase values is essential for comparison of values after pesticide application.     

Occupational health in Australia

Australia is a developed country in the Asia-Pacific Region with a large land area but a small population. Its main economic activities are mining, agriculture and manufacturing, with its service and high-technology industries being the fastest growing sectors in recent years. The regulation and enforcement of Occupational Health and Safety policies are mainly administered by the Industrial Relations Departments of eight State and Territory jurisdictions in the country. A National Occupational Health and Safety Commission coordinates occupational health and safety at the Commonwealth level. In 1987 the six occupational health and safety priorities in Australia were listed as occupational back pain, management of chemicals used at work, occupational noise-induced hearing loss, occupational skin disorders, occupational cancer and mechanical equipment injury. Australia has probably the highest incidence of malignant mesothelioma in the world, although the use of asbestos has been largely phased out. There was an almost explosive “epidemic” of repetition strain injury in the 1980s. Approximately 500 work-related fatalities and 10,000 work-related injuries are notified for workers' compensation every year. In addition, it is estimated that there are several thousand cases of work-related diseases every year, many of which go unreported. Occupational physicians undergo 4 years of specialisation training. Occupational hygienists, nurses and ergonomists receive training supervised by their respective professional organisations. Received: 2 March 1998 / Accepted: 10 March 1998     

Do men with normal testosterone–oestradiol ratios benefit from letrozole for the treatment of male infertility?

Research question

Previous studies of aromatase inhibitors on male infertility have focused on men with low testosterone–oestradiol ratio of less than 10. Can aromatase inhibitors improve spermatogenesis in men with idiopathic male infertility with normal testosterone–oestradiol ratio?

Prevalence and risk factors of depression in the elderly nursing home residents in Singapore

Objectives: Depression is a common health problem in elderly nursing home (NH) residents and is often under-recognized and under-treated. This study aimed to determine the prevalence rates of depression and identify the risk factors associated with depression in the elderly NH population in Singapore.

Methods: A sample of 375 residents in six NHs in Singapore, aged 55 years and above, was assessed with the Structural Clinical Interview (SCID), based on the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria. The association of demographic, functional and health-related characteristics with depression was examined using multivariate logistic regression analyses.

Results: Overall point prevalence for depression in the elderly NH residents was found to be 21.1% (95% confidence intervals (CI): 17.1%–25.6%). The prevalence rate for minor depression in the elderly NH residents was 14.4% (95% CI: 11.1%–18.5%) and 6.7% (95% CI: 4.5%–9.8%) for major depression. Significant risk factors that were found to be associated with depression were length of stay for more than 2 years, known history of depression, pain, and no or lack of social contact.

Conclusion: The prevalence rates for depression were high among NH residents in Singapore. More attention is needed to care for the psychosocial needs of elderly NH residents in Singapore.     

Identification of neutralizing linear epitopes from the VP1 capsid protein of Enterovirus 71 using synthetic peptides

Enterovirus 71 (EV71) is the main causative agent of Hand, foot and mouth disease (HFMD) and has been associated with severe neurological diseases resulting in high mortalities. Currently, there is no vaccine available and treatment is limited to palliative care. In this study, antisera were raised in mice against 95 overlapping synthetic peptides spanning the VP1 capsid protein of EV71. Two peptides, SP55 and SP70, containing amino acid 163-177 and 208-222 of VP1, respectively, are capable of eliciting neutralizing antibodies against EV71 in the in vitro microneutralization assay. SP70 was identified to be particularly potent in eliciting a neutralizing antibody titer comparable to that obtained with a whole virion-immune serum. Immunization of mice with either SP55 or SP70 triggered an EV71-specific IgG response as high as that obtained with the whole virion as immunogen. The IgG sub-typing revealed that the neutralizing antibodies elicited by both synthetic peptides are likely belonging to the IgG1 sub-type. Alignment with databases showed that the amino acid residues of SP70 are highly conserved amongst the VP1 sequences of EV71 strains from various sub-genogroups. Altogether, these data indicate that SP70 represents a promising candidate for an effective synthetic peptide-based vaccine against EV71.     

Onset of cardiac function during early mouse embryogenesis coincides with entry of primitive erythroblasts into the embryo proper

When cardiac function and blood flow are first established are fundamental questions in mammalian embryogenesis. The earliest erythroblasts arise in yolk sac blood islands and subsequently enter the embryo proper to initiate circulation. Embryos staged 0 to 30 somites (S) were examined in utero with 40- to 50-MHz ultrasound biomicroscopy (UBM)-Doppler, to determine onset of embryonic heartbeat and blood flow and to characterize basic physiology of the very early mouse embryonic circulation. A heartbeat was first detected at 5 S, and blood vascular flow at 7 S. Heart rate, peak arterial velocity, and velocity-time integral showed progressive increases that indicated a dramatically increasing cardiac output from even the earliest stages. In situ hybridization revealed an onset of the heartbeat coincident with the appearance of yolk sac-derived erythroblasts in the embryo proper at 5 S. Early maturation of the circulation follows a tightly coordinated program.